Textile fabric treatment



United States Patent Int. Cl. D06c 27/00 US. Cl. 2-243 5 Claims ABSTRACT OF THE DISCLOSURE Permanent-crease, wash-and-wear garments are made by impregnating a cellulose fiber-containing fabric with a solution of an unsymmetrical cross-linking and creaseproofing agent having a vinyl group and a reactive group capable of reaction with cellulose to form a cellulose ether or ester in the presence of a chemical catalyst without reacting the vinyl group, reacting the aforesaid reactive group with the cellulose of the fabric, washing the fabric to remove unreacted chemicals, cutting and shaping the fabric to form garments, and treating the shaped garments with high energy ionizing radiation to polymerize the vinyl group of the cross-linking agent.

This invention relates to the treatment of cotton or cellulosic textile fabrics. In One specific aspect, it relates to the preparation of permanent-crease, wash-and-wear garments.

More than three billion linear yards of fabric are utilized each year to produce wrinkle-resistant garments of the wash-and-wear type. The fabric, usually made of cotton or cotton blended with other materials, is chemically treated to modify the cotton and increase its resistance to deformation. Conventional treating agents possess reactive groups at each end of the molecule capable of reaction with cellulosic hydroxyl groups. The treatment connects or cross-links the long-chain cellulose molecules by means of a chemical reaction between the treating agent and hydroxyl groups on adjacent cellulose molecules. Cross-linking is generally believed to prevent slippage, or viscous flow, during deformation and hence inhibit wrinkling of the fabric.

The usual practice in the preparation of wash-an'd-wear fabrics is to impregnate or pad the fabric with a water solution of the cross-linking agent. After drying at a relatively low temperature, e.g., 230 F., the impregnated fabric is heated for two to five minutes at a temperature of about 325 F. to complete cross-linking. After this final curing step, the residual chemicals are removed by washing and the fabric is ready for garment manufacture. The cross-linking treatment is usually the final step in a fabric finishing process since the cross-linked fabric has a lowered permeability to dyestuffs and other treating agents.

When it is desired to make permanent creases in garments such as mens trousers, the fabric is impregnated and dried as above but sent to the garment manufacturer to be made into garments prior to final curing. The fabric is cut and sewn, the desired creases located and the assembled garments pressed to shape. The creases present in the completed garments are fixed and made relatively long lasting by heat curing at 350 F. This procedure is known in the garment trade as a delayed cure.

Higher temperatures are generally employed in the curing of garments when permanent creases are desired as compared with the temperatures used to cure other wash-and-wear garments. For if the same combination of normall reactive cross-linking agents and catalysts were applied to the fabric intended for delayed curing as are used in fabrics intended for immediate curing, the chemicals would tend to cure during shipment and storage prior to manufacture. Such premature cuirng would make curing at the appropriate time less effective or even ineffective. In order to avoid this, relatively slow curing systems requiring longer curing times at higher temperatures are used in fabrics intended for delayed cure. Since folded portions of garments such as cuffs or collars which comprise several layers of fabric are more slowly penetrated by heat than the single layers of fabric, other portions of the garments tend to be over-cured under the conditions necessary for completely curing the folded parts. This results in excessive loss of strength and decreased abrasion resistance in the fabric, and the color of many dyed fabrics are adversely affected by these more drastic curing conditions.

Garments made in the above described manner generally are not Washed before entering the market. Various problems arise from the fact that the fabric is shipped, stored, and handled while still impregnated with unreacted or incompletely reacted chemicals. For example, such chemicals may develop unpleasant odors during storage and there is the possibility of dermatitis in persons handling the cloth.

It is, therefore, an object of the present invention to provide a new and improved method for the preparation of permanent-crease, wash-and-wear garments.

It is a further object of the invention to provide permanent-crease, wash-and-wear garments which are free of residual or unreacted chemical agents.

It is another object of the present invention to provide a method for the preparation of permanent-crease, washand-wear garments which does not require the use of heat in the final curing step.

These and other desirable objectives and advantages are obtained by operation in accordance with the method of the present invention which utilizes an unsymmetrical cross-linking agent that contains a group that is chemically reactive toward cellulosic hydroxyl groups and an un saturated group (e.g., vinyl) that can be polymerized by means of ionizing radiation. Cross-linking agents of this type are reacted with the fabric, usually in the presence of a catalyst. The modified fabrics containing cotton cellulose with unsaturated groups chemically attached thereto, after being washed free of residual unreacted chemicals, are manufactured into garments carrying desired creases -or pleats and then cross-linked through these unsaturated groups by means of ionizing radiation.

More specifically, the present invention is a method for making permanent-crease, wash-and-wear garments which comprises impregnating a cellulose-containing fabric with a solution of an unsymmetrical cross-linking agent having a reactive group capable of reaction with cellulose and a vinyl group, reacting the aforesaid reactive group with the cellulose of the fabric, washing the fabric to remove unreacted chemicals, cutting and shaping the fabric to form garments, and treating the shaped garments with ionizing radiation to polymerize the vinyl group of the cross-linking agent.

My invention is further illustrated by the following general discussion and examples:

Any vinyl substituted cross-linking agent having another function capable of reaction with cellulose and cellulose derivatives and capable of later cross-linking by radiation, or mixtures of such cross-linking agents, can be used in the process of my invention. A preferred class of such cross-linking agents includes functional group bearing derivatives of unsaturated acids such as acrylic and methacrylic acid. Cross-linking agents of particular interest are acrylic acid which has a carboxyl group capable of esterification with cellulose, glycidyl acrylate which contains an epoxy group reactive with cellulosic hydroxyl groups and methylol acrylamide, the methylol group of which condenses with cellulosic hydroxyl groups under acidic conditions.

Cross-linking agents suitable for use in the process of the present invention are unsymmetrical in the sense that, in a given cross-linking agent, the functional groups present are of widely different reactivities. This difference in reactivities is necessary for use in a two-step process. The cellulose-reactive groups are first reacted with the cellulosic hydroxyl groups to yield a fabric having a cellulose backbone and pendant vinyl groups. These pendant vinyl groups are stable, particularly in the presence of a polymerization inhibitor, and will not polymerize spontaneously. After the fabric has been processed and in the presence of ionizing radiation, the vinyl groups will polymerize and cross-link adjacent cellulose moieties.

In practicing the process of the present invention, the fabric to be converted to the permanent-crease, washand-wear garment is impregnated by means of a solution, usually a concentrated aqueous solution, of the crosslinking agent. The treating solution also contains roughly 1% of an appropriate catalyst, usually acidic, to promote reaction of the cross-linking agent with the cellulosic hydroxyl groups. Typical acid catalysts are organic acids such as acetic acid and salts having an acidic reaction such as ammonium chloride, acid sulfates and other salts of strong acids and weaker bases. The treating solution may also contain a polymerization inhibitor to minimize premature polymerization of the vinyl group. The concentration of the treating solution is adjusted so that the fabric will pick up at least about 5% by weight of the cross-linking agent.

The cross-linking agent impregnated fabric is washed to remove any unreacted cross-linking agent, catalyst and any other residual chemical agents that may be present. The fabric, after drying, is ready for cutting, sewing, shaping, pressing and the other steps utilized in garment preparation. The treated fabric is storage stable during the several weeks or months which elapse in the normal course of events before the fabric is actually made into garments.

After the garment has been prepared and the desired permanent creases pressed in, the vinyl groups present are polymerized by means of ionizing radiation at room temperature. Gamma rays are the preferred form of ionizing radiation for use in the practice of the present invention but electron accelerators should also be practical. The most convenient sources of gamma rays currently available are radioactive isotopes of cobalt and various uranium fission products. The amount of radiation employed should be sufficient to cause substantially all of the vinyl groups present to polymerize. Any excess of radiation, which would tend to degrade the fabric, should be avoided. The extent of treatment will be dependent on the energy of the treating source used. Satisfactory results are obtained using about 2 megarads of ionizing radiation.

The process of the present invention uses ionizing radiation at room temperature in place of the generally high-temperature cure in the final step. Permanent-crease cellulosic garments finished in the conventional manner at elevated temperatures are generally less durable than the unfinished or starting fabric. Fabrics treated according to the process of the present invention are more resistant to abrasion and tearing as well as being resistant to creasing.

The process of the present invention is applicable to cellulose-containing textile fabrics generally. The term textile-fabrics as used herein is meant to include textile fabrics of all kinds including woven and non-woven fabrics, knitted goods, et cetera. The fabric may contain or be made from a natural cellulose material such as cotton or a regenerated cellulose material such as rayon.

My invention is further illustrated by means of the following non-limiting examples:

Scoured and bleached x 80 cotton print cloth was used for all experiments. The amounts of the various reactants added were determined by percent weight gain after washing and drying the fabric. The Monsanto method was used for crease-recovery angle determinations and tearing strengths were made on an Elmendorf tester. The crease-recovery angle (CRA) is a measure of the fabrics resistance to deformation. Crease-recovery angles at 250 and above are commercially acceptable.

N-methylol acrylamide was prepared by reacting equimolar portions of formaldehyde and acrylamide in aqueous solution. The reaction was carried out at 80 C. for six hours with the pH adjusted to 10.5 by means of potassium hydroxide. After neutralization with hydrochloric acid, the solution was used without further treatment for padding the samples.

The fabric was impregnated with a water solution of 14% N-methylol acrylamide as the reactant, 0.5% ammonium chloride as the condensation catalyst, and 1% hydroquinone as the polymerization inhibitor. The dumpdried fabric was heated for 5 minutes at C., washed and dried. The gain in weight of the impregnated fabric was 6.8%. This one-step treatment decreased tear strengths by about 20% and produced only slight increases in crease-recovery angles.

The polymerization reactions were carried out under purified nitrogen containing less than 0.002% of oxygen using a 2000 curie cobalt-60 radiation source with an effective exposure dose rate of 250,000 roentgens per hour. The acrylamidomethylated print cloth was given a two-megarad irradiation dose at three relative humidity (RH) levels. The results are summarized below:

In another experiment, the cotton fabric was impregnated with a water solution of 16% methylol acrylamide, 0.5% ammonium chloride, and 1% hydroquinone and dried in air. The fabric was then heated for three minutes at 320 F., rinsed and dried. The fabric gained 6.7% by weight. Strips of the treated fabric and untreated controls were creased in both the warp and filling direction with a warm iron. The strips were cut in half across the crease and one-half of each strip was irradiated as above. All of the fabric strips were agitated for 8 hours in a 5% soap solution, rinsed, and dried. The creases in the unirradiated strips and in the control strips were almost completely removed; those in the irradiated strips were sharp and well defined.

Procedural variations falling within the ambit of the present invention will be apparent to those skilled in the art. The scope of my invention is as in the appended claims.

I claim:

1. A method for making permanent-crease, wash-andwear garments which comprises impregnating a cellulose fiber-containing fabric with a solution of an unsymmetrical cross-linking and crease-proofing agent having a vinyl group and a reactive group capable of reaction with cellulose to form a cellulose ether or ester in the presence of a chemical catalyst without reacting the vinyl group, reacting the aforesaid reactive group with the cellulose of the fabric, washing the fabric to remove unreacted chemicals, cutting and shaping the fabric to form garments, and treating the shaped garments with high energy ionizing radiation to polymerize the vinyl group of the cross-linking agent.

2. A method according to claim 1 wherein the cellulose fiber-containing fabric is a cotton fabric.

3. A method according to claim 1 wherein the cross- 5 linking agent is N-methylol acrylamide.

4. A method according to claim 1 wherein irradiation is effected in the absence of oxygen.

5. A method for making permanent-crease wash-andwear garments which comprises impregnating a cellulose fiber containing cotton fabric with a solution of N- methylol acrylamide, reacting the methylol group of the N-methylol acrylamide with cellulosic hydroxyl groups of the cotton fabric in the presence of a chemical catalyst without reacting the vinyl group, washing the fabric to remove unreacted chemicals, cutting and shaping the fabric to form garments, and treating the shaped garments with high energy ionizing radiation to polymerize the vinyl groups of the N-rnethylol acrylamide.

References Cited UNITED STATES PATENTS 6 2,959,569 11/1960 Warrick. 3,001,922 9/1961 Zirnrn. 3,206,273 9/ 1965 Munzel 8--116 3,254,939 6/1966 Munzel 81 16 3,254,940 6/1966 Heberlein et al. 8116 XR 3,256,166 6/1966 Pfeiffer. 3,298,979 1/1967 Hagemeyer et a1.

OTHER REFERENCES Tesoro et al.: Textile Research Journal, February 1963, pp. 93-107.

NORMAN G. TORCHIN, Primary Examiner.

5 J. CANNON, Assistant Examiner.

U.S. Cl. X.R. 

